Code review feedback

src/EditorFeatures/Core/Implementation/IntelliSense/AsyncCompletion/ItemManager.cs

@@ -269,6 +269,7 @@ private static bool IsAfterDot(ITextSnapshot snapshot, ITrackingSpan applicableT
             // Ask the language to determine which of the *matched* items it wants to select.
             var matchingItems = itemsInList.Where(r => r.FilterResult.MatchedFilterText)
                                            .Select(t => t.FilterResult.CompletionItem)
+                                           .Where(r => !r.DisplayText.StartsWith("★"))
                                            .AsImmutable();
 
             var chosenItems = filterMethod(matchingItems, filterText);
@@ -291,8 +292,7 @@ private static bool IsAfterDot(ITextSnapshot snapshot, ITrackingSpan applicableT
             {
                 selectedItemIndex = itemsInList.IndexOf(i => Equals(i.FilterResult.CompletionItem, bestItem));
                 if (selectedItemIndex > -1 &&
-                    bestItem != null &&
-                    matchingItems.Where(r => !r.DisplayText.StartsWith("★")).Count() == 1 &&
+                    matchingItems.Length == 1 &&
                     filterText.Length > 0)
                 {
                     uniqueItem = highlightedList[selectedItemIndex].CompletionItem;

src/EditorFeatures/Test2/IntelliSense/CSharpCompletionCommandHandlerTests.vb

@@ -4851,6 +4851,55 @@ class C
             End Using
         End Function
 
+        ' Implementation for the Modern completion only
+        <InlineData(CompletionImplementation.Modern)>
+        <WpfTheory, Trait(Traits.Feature, Traits.Features.Completion)>
+        Public Async Function TestSendCommitIfUniqueWithIntelliCodeAndDuplicateItemsFromIntelliCode(completionImplementation As CompletionImplementation) As Task
+            Dim provider = New IntelliCodeMockWeirdProvider()
+            Using state = TestStateFactory.CreateCSharpTestState(completionImplementation,
+                              <Document>
+class C
+{
+    void Method()
+    {
+        var s = "";
+        s.Len$$
+    }
+}
+                              </Document>, {provider})
+
+                state.SendCommitUniqueCompletionListItem()
+                Await state.AssertNoCompletionSession()
+                Assert.Contains("s.Length", state.GetLineTextFromCaretPosition(), StringComparison.Ordinal)
+            End Using
+        End Function
+
+        ' Implementation for the Modern completion only
+        <InlineData(CompletionImplementation.Modern)>
+        <WpfTheory, Trait(Traits.Feature, Traits.Features.Completion)>
+        Public Async Function TestSendCommitIfUniqueInInsertionSessionWithIntelliCodeAndDuplicateItemsFromIntelliCode(completionImplementation As CompletionImplementation) As Task
+            Dim provider = New IntelliCodeMockWeirdProvider()
+            Using state = TestStateFactory.CreateCSharpTestState(completionImplementation,
+                              <Document>
+class C
+{
+    void Method()
+    {
+        var s = "";
+        s$$
+    }
+}
+                              </Document>, {provider})
+
+                state.SendTypeChars(".len")
+                Await state.AssertCompletionSession()
+                state.AssertCompletionItemsContainAll({"Length", "★ Length3", "★ Length2"})
+                state.SendCommitUniqueCompletionListItem()
+                Await state.AssertNoCompletionSession()
+                Assert.Contains("s.Length", state.GetLineTextFromCaretPosition(), StringComparison.Ordinal)
+            End Using
+        End Function
+
         Private Class MultipleChangeCompletionProvider
             Inherits CompletionProvider
 
@@ -4903,5 +4952,23 @@ class C
                 Return True
             End Function
         End Class
+
+        ' Simulates a situation where IntelliCode provides items not included into the Rolsyn original list.
+        ' We want to ignore these items in CommitIfUnique.
+        ' This situation should not happen. Tests with this provider were added to cover protective scenarios.
+        Private Class IntelliCodeMockWeirdProvider
+            Inherits CompletionProvider
+
+            Public Overrides Function ProvideCompletionsAsync(context As CompletionContext) As Task
+                context.AddItem(CompletionItem.Create(displayText:="★ Length2", filterText:="Length2"))
+                context.AddItem(CompletionItem.Create(displayText:="Length", filterText:="Length"))
+                context.AddItem(CompletionItem.Create(displayText:="★ Length3", filterText:="Length3"))
+                Return Task.CompletedTask
+            End Function
+
+            Public Overrides Function ShouldTriggerCompletion(text As SourceText, caretPosition As Integer, trigger As CompletionTrigger, options As OptionSet) As Boolean
+                Return True
+            End Function
+        End Class
     End Class
 End Namespace